Postdoc: Modeling Adsorption of Aqueous Solutions on Activated Carbon Surfaces

水和水/X混合物在模型活性炭上的吸附将根据需要使用有偏差采样的大规范蒙特卡罗技术进行研究。由于不同物种之间的氢键，这样的模拟要求很高；这种键的寿命相对较长，需要长时间的模拟来确保遍历行为。大型系统也需要避免规模效应。本项目将研究活性炭表面上的纯水，其中含氧表面位点附着在表面上，可以与水分子中的H原子形成氢键。将研究地点密度、地点种类和地点在地表的几何排列变化的影响。特别是这些变量对吸附、填充机制和吸附热的影响将引起人们的兴趣。随后将对这些表面上的水/X混合物进行研究。一开始，X是碳氢化合物，甲烷或者苯。烃类和水的孔隙填充机制可能完全不同，因此，位置参数的变化可能会对其中一种组分的孔隙选择性产生决定性影响，并可能出现选择性反转。以后的研究将包括X是醋酸的情况。苯和乙酸都具有实际意义，因为它们是EPA优先考虑的污染物。由于水和乙酸都可以与表面结合，因此对乙酸的选择性机制将是微妙的，很难在模拟之前预测。将在康奈尔大学的IBM SP/2上为这些模拟开发并行代码。

The adsorption of water and water/X mixtures on model activated carbons will be studied using Grand Canonical Monte Carlo techniques with biased sampling as needed. Such simulations are very demanding because of the hydrogen-bonding between the various species; such bonds are relatively long lived, and long simulations are needed to ensure ergodic behavior. Large systems are also needed to avoid size effects. This project will study pure water on an activated carbon surface, in which oxygenated surface sites are attached to the surface and can H-bond to the H atom in the water molecules. The effect of variation in the density of sites, species of sites, and geometric arrangement of sites on the surface will be studied. In particular the effect of these variables on the absorption, filling mechanism, and heats of adsorption will be of interest. This will be followed by studies of water/X mixtures on such surfaces. Initially, X will be a hydrocarbon, methane or benzene. The pore filling mechanism for the hydrocarbon and water are expected to be completely different, so that variation of the site parameters is likely to have a decisive effect on the selectivity of the pore for one of the components, and selectivity inversion is likely to be seen. Later studies will include the case where X is acetic acid. Both benzene and acetic acid are of practical interest, since they are EPA priority pollutants. The selectivity mechanism for acetic acid will be subtle and difficult to predict in advance of the simulations, since both water and acetic acid can bond to the surface. Parallel codes will be developed for these simulation on the IBM SP/2 at Cornell.